I don't see why everyone complains about killing off their fireflies with unstable gas when upgraded. Just wait until the opponent has low enough health!
So what is the sense to wait, when FF+EpiDamsefly can deal the same damage and You don't need waste 5

and one turn for UG

Of course sometimes UG is useful, but when we talk about FFQ then UG didn't work good and gives more problems (kill all field) than advantage, especially when You should use SkyBlitz which is faster and better here.
Concept

for unupped and

for upped FF is much better and more reasonable than situation which we have today. I think that it will be also good decision turning 4|2 for

FF into 3|4 (can alive 2 UG more) and increasing stats for

FF into 4|2. Then it is more balanced...
Unupped FF - 3|4 - generate

Upped FF - 4|2 - generate

(or maybe

)
Don't You think that it is better?